Voilà !

The first version of the box is ready for the tests, it still misses a few accessories but the system is useful and usable :-D

The main features are here, I'm waiting for the AC voltmeter to be delivered.

The passive series loads could be better but we'll see in practice if the design must be changed. After all, everything can be re-wired so there is no need to worry about "getting it right at the first try".